Effect of Physical Activity Intervention on Gait Speed by Frailty Condition: A Randomized Clinical Trial

Objectives: There is uncertainty about effects of physical activity on physical performance, such as gait speed, among community-dwelling older adults according to their physical frailty status. We determined whether a long-term, moderate-intensity physical activity program was associated with different responses on gait speed over 4 m and 400 m based on physical frailty status. Design: Post hoc analysis from the Lifestyle Interventions and Independence for Elders (LIFE) (NCT01072500), a single-blind randomized clinical trial testing the effect of physical activity intervention compared with health education program. Setting and Participants: We analyzed data on 1623 community-dwelling older adults (78.9 ± 5.2 years) at risk for mobility disability. Methods: Physical frailty was assessed at baseline using the Study of Osteoporotic Fractures frailty index. Gait speed over 4 m and 400 m was measured at baseline, and 6, 12, and 24 months. Results: We estimated significantly better 400-m gait speed at 6, 12, and 24 months for nonfrail older adults in the physical activity group, but not for frail participants. Among frail participants, physical activity showed a potentially clinically meaningful benefit on 400-m gait speed at 6 months (0.055; 95% CI 0.016–0.094; P = .005), compared with the healthy educational intervention, only in those who, at baseline, were able to rise from a chair 5 times without using their arms. Conclusions and Implications: A well-structured physical activity program produced a faster 400-m gait speed potentially able to prevent mobility disability among physically frail individuals with preserved muscle strength in lower limbs.